The National Institutes of Health estimates that erectile dysfunction strikes as many as 30 million men in the United States. Its prevalence does increase with age — 4 percent of men in their 50s are affected by ED, 17 percent in their 60s, and 47 percent of those over 75. But research has also found that 5 percent of those affected were between 20 and 39.
There is also a significant population, which has psychogenic sexual dysfunction, which is likely in a situation of marital conflict, which commonly exists in the families of alcoholics.[18] There is some evidence of this with more than a third of the subjects reporting dissatisfaction with their spouses' responses and / or decreased frequency. This cannot be conclusive without data on nocturnal erection or sexual activity in alternate situations. One of the limitations of this exploratory study is that marital functioning was not specifically assessed.

Surgery for erectile dysfunction is usually considered only after all other options have failed. The two surgical options include the insertion of a semi-rigid rod or the implantation of a three-piece inflatable prosthesis. Penile prosthesis implantation has low infection, complication, and malfunction rates. However, since placement of an implant requires permanent injury to the erectile tissue of the penis, implant treatment is considered irreversible.


No matter what the cause of erectile dysfunction, it is likely to cause feelings of stress and other emotional reactions. It’s also not uncommon for erection problems to cause tension in a relationship, particularly if one or both partners withdraws emotionally and the problem is not talked about. And it’s possible for a man’s renewed ability to have intercourse after a period of no sexual activity to stir up relationship issues.
The first goal in treating ED is to manage your diabetes. This includes keeping your blood sugar and blood pressure under control. If ED persists, treatments are available. While oral medications are a common first therapy, they don’t work for all men with diabetes. The penile implant may be an option. The implant is concealed inside the body. It offers support for an erection whenever and wherever desired.
But don’t panic. ED can be caused by a number of factors, from depression and medication side effects to high blood pressure, high cholesterol, low testosterone levels, Peyronie’s disease, nerve damage, performance anxiety, heart disease, diabetes, and more. Even better, many of these ED causes are treatable with medication and simple lifestyle changes. It’s important to know the root cause of your erectile dysfunction in order to treat it in the fastest, most effective way possible. Here are the 5 most common causes of erectile dysfunction.
Phosphodiesterase inhibitors: This class of medications includes sildenafil, tadalafil, and vardenafil. They work by inhibiting an enzyme called phosphodiesterase type 5 (PDE-5), allowing more blood to enter the penis and helping to produce an erection. These medications are often taken before sex and will cause an erection only when the man is sexually stimulated.
"We used to think that ED in young men was 90 percent psychological, but we now know that most cases are caused by a combination of risk factors. Erectile function depends on hormones, blood supply, nerve function, and psychological health,” said Run Wang, MD, professor of urology at The University of Texas Health Science Center in Houston and director of sexual medicine at MD Anderson Cancer Center.
Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
ICI therapy often produces a reliable erection, which comes down after 20-30 minutes or with climax. Since the ICI erection is not regulated by your penile nerves, you should not be surprised if the erection lasts after orgasm. The most common side effect of ICI therapy is a prolonged erection. Prolonged erections (>1 hour) can be reversed by a second injection (antidote) in the office.
The penis contains three cylinders, the two corpora cavernosa, which are on the top of the penis (see figure 1 below). These two cylinders are involved in erections. The third cylinder contains the urethra, the tube that the urine and ejaculate passes through, runs along the underside of the penis. The corpus spongiosum surrounds the urethra. Spongy tissue that has muscles, fibrous tissues, veins, and arteries within it makes up the corpora cavernosa. The inside of the corpora cavernosa is like a sponge, with potential spaces that can fill with blood and distend (known as sinusoids). A layer of tissue that is like Saran Wrap, called the tunica albuginea, surrounds the corpora. Veins located just under the tunica albuginea drain blood out of the penis.
For oral erectile dysfunction medicines to work as desired, they must be used properly in the first place. This means taking the medicine 30–45 minutes before engaging in sexual intimacy; taking the drug on an empty stomach or at least avoiding a heavy or high-fat meal before taking the drug (this is especially important when using sildenafil); and engaging in adequate genital stimulation before attempting intercourse. Drinking small amounts of alcohol (one to two drinks) should not compromise the effectiveness of erectile dysfunction medicines, but larger amounts of alcohol can diminish a man’s ability to have an erection.
Lifestyle changes: One of the first things a young man can do to potentially improve or eliminate ED is make positive choices that will also have an impact on the rest of his life. Some changes a man can consider include increasing exercise, eating a heart-healthy diet, quitting smoking, and drinking alcohol only in moderation. Where a man has relationship problems, seeking counseling may also be helpful.

Before taking any medication for erectile dysfunction, including over-the-counter supplements and herbal remedies, get your doctor's OK. Medications for erectile dysfunction do not work in all men and might be less effective in certain conditions, such as after prostate surgery or if you have diabetes. Some medications might also be dangerous if you:


Research is mixed on the effectiveness of acupuncture as an erectile dysfunction cure, but one study published in November 2013 in the Journal of Alternative and Complementary Medicine found that acupuncture can be beneficial for men experiencing erectile dysfunction as a side effect of antidepressants, including selective serotonin reuptake inhibitors (SSRIs) and serotonin noradrenaline reuptake inhibitors (SNRIs).
Although ED and diabetes are two separate conditions, they tend to go hand in hand. Half of men with diabetes will experience ED within 10 years of their diagnosis.8 For some men, ED may be the first symptom of diabetes even if they have not yet been diagnosed, particularly in men younger than 45.6 Left untreated, ED can damage self-confidence and relationships.
To give you some evidence of the link between anxiety, stress, and ED consider the results of a study published in a 2015 edition of Comprehensive Psychiatry. In a study of case records for 64 men with erectile dysfunction or premature ejaculation, there was a significant link between ED and anxiety disorders or depression. Of the 64 participants, 8 had comorbid depressive disorders and 15 had anxiety disorders. In the majority of patients, these disorders predated the onset of sexual dysfunction which suggests that the disorders may have been a contributing factor.

ED usually has something physical behind it, particularly in older men. But psychological factors can be a factor in many cases of ED. Experts say stress, depression, poor self-esteem, and performance anxiety can short-circuit the process that leads to an erection. These factors can also make the problem worse in men whose ED stems from something physical.


This patient has thoroughly researched erectile dysfunction on the internet and has a powerful knowledge base from which he draws reference. He is also emotionally labile. The most urgent recommendation for this patient is that he seek appropriate psychiatric treatment to help in management of his psychiatric conditions and suicidal ideation. It was also recommended that he seek care with a sexual therapist to work through additional issues related to his “addiction” to masturbation. During his urologic visit we performed both cold and hot perception testing and biothesiometer, which were normal. He was displeased with these findings as they were incongruent with his chief complaints; normal results caused him to become tearful. A penile ultrasound was performed without injection of a pharmacologic agent to assess the appearance of his cavernous tissue and cavernous arteries, which had normal appearance and measurement, respectively, on ultrasound. (This quick bedside procedure has the potential to be both diagnostic and therapeutic for the patient; the importance of this cannot be underestimated).
It's also important to remember that your mental health plays as much a part of your sexual ability as your physical health. Stress and other mental health concerns can cause or make erectile dysfunction worse. Minor health problems may slow your sexual response, but the accompanying anxiety that comes with the slow sexual response can shut things down entirely.
Smoking.   Smoking and erectile dysfunction are related as smoking leads to plaque build up in the arteries called cardiovascular disease, which restricts blood flow through the veins.  Arterial sclerosis from smoking restricts blood flow, and thus can prevent the massive amount of blood required for you to achieve an eretion, resulting in erectile dysfunction.
Obesity. Obesity itself is not a risk factor for ED — but there is a connection. “The bigger concern is that obesity can lead to type 2 diabetes or vascular diseases, which are risk factors for ED,” says Montague. Morbid obesity, a term used to classify individuals who are significantly overweight, can cause hormonal changes that are triggered by excess body fat. In addition, obesity can put physical limitations on sexual intercourse.

Erectile dysfunction may be an unpleasant condition that no one really wants to talk about, failing to acknowledge it won’t make the problem go away. Your best defense against health problems like this is to learn everything you can about it so you can tackle the problem at the root. If you’re ready to stop living in embarrassment about your sexual function, become an advocate for yourself and your own health and talk to your doctor.
Dr. Anna Murray, of the University of Exeter Medical School, is co-lead author on the study. She said: “Erectile dysfunction affects at least one in five men over 60, yet up until now little has been known about its cause. Our paper echoes recent findings that the cause can be genetic, and it goes further. We found that a genetic predisposition to type 2 diabetes is linked to erectile dysfunction. That may mean that if people can reduce their risk of diabetes through healthier lifestyles, they may also avoid developing erectile dysfunction.”
Luckily, awareness of ED as a significant and common complication of diabetes has increased in recent years, mainly because of increasing knowledge of male sexual function and the rapidly expanding armamentarium of novel treatments being developed for impotence. Studies of ED suggest that its prevalence in men with diabetes ranges from 35–75% versus 26% in general population. The onset of ED also occurs 10–15 years earlier in men with diabetes than it does in sex-matched counterparts without diabetes.
Treatments include psychotherapy, adopting a healthy lifestyle, oral phosphodiesterase type V (PDE5) inhibitors (Viagra, Levitra, Cialis, Stendra, and Staxyn), intraurethral prostaglandin E1 (MUSE), intracavernosal injections (prostaglandin E1 [Caverject, Edex], Bimix and Trimix), vacuum devices, penile prosthesis and vascular surgery, and (in some cases) changes in medications when appropriate.
Erectile dysfunction is no laughing matter. And although it is not an easy thing to talk about, there are trained professionals who can give you good advice about what may be the cause of your current predicament. Many men like to talk about sex, but like women, they may find it harder to talk about sex when it is not going well. You won’t be judged or talked about at BPAS. We are here to help you with some of the more private things in life.

Cardiovascular diseases: The most common cause of cardiovascular diseases in the United States is atherosclerosis, the narrowing and hardening of arteries that reduces blood flow. Atherosclerosis (a type of vascular disease) typically affects arteries throughout the body; hypertension, high blood cholesterol levels, cigarette smoking, and diabetes mellitus aggravate atherosclerosis. Hardening of the arteries to the penis and pelvic organs, atherosclerosis, causes insufficient blood flow into the penis. There is a close correlation between the severity of atherosclerosis in the coronary arteries and erectile dysfunction. For example, men with more severe coronary artery atherosclerosis (hardening of the arteries in the heart) also tend to have more erectile dysfunction than men with mild or no coronary artery atherosclerosis. Some doctors suggest that men with new onset erectile dysfunction undergo evaluation for silent coronary artery diseases (advanced coronary artery atherosclerosis that has not yet caused angina or heart attacks).
Getting (and maintaining) an erection requires a surprising amount of things to go right. You have to get aroused, then pass that signal from your brain, through your nerves and hormones, to your blood vessels and muscles before an erection can even happen. If one thing goes wrong in that complicated exchange between your cardiovascular, and nerve system, and your hormone levels, blood vessels, and even your mood the result is usually erectile dysfunction. In other words, getting an erection is hard.
That doesn’t mean you need to cut back completely — most experts say moderation is key. But what's “moderation” exactly? According to the U.S. Centers for Disease Control and Prevention (CDC), moderate drinking is no more than two drinks a day for men (and one drink a day for women). The liver can only break down the amount of alcohol in about one standard-size drink an hour, so regularly drinking more than that means that toxins from alcohol can build up in your body and affect your organs, including those involved in sex.
We are writing this commentary to provide urologists with additional information regarding ED in young men and to open the discussion for new approaches to treatment of ED in young men. Hypertonic cavernous smooth muscle is an organic etiology of erectile dysfunction and should be considered in the differential diagnosis for these young men. Developing a system to explain the pathophysiologic mechanism of the dysfunction may make it easier to effectively treat these complex patients.

As you can imagine, these symptoms can make it difficult to take pleasure in much of anything, let alone sex. A study published in a 1998 edition of Psychosomatic Medicine shows a clear link between depression and erectile dysfunction in men. Using data obtained from the Massachusetts Male Aging Study, researchers were able to conclude that a relationship between depressive symptoms and erectile dysfunction existed and was independent of aging and demographics.
There is also a significant population, which has psychogenic sexual dysfunction, which is likely in a situation of marital conflict, which commonly exists in the families of alcoholics.[18] There is some evidence of this with more than a third of the subjects reporting dissatisfaction with their spouses' responses and / or decreased frequency. This cannot be conclusive without data on nocturnal erection or sexual activity in alternate situations. One of the limitations of this exploratory study is that marital functioning was not specifically assessed.

If on one hand, depression and anxiety can lead to ED, drugs commonly used for their treatment can cause ED, as well. Sexual dysfunctions are common side effects of several psychotropic drugs that can disrupt sexual health by several different mechanisms (83). In particular, ED has been reported in subjects using serotonin selective re-uptake inhibitors (SSRI), lithium and benzodiazepines (83). SSRI are associated with a broad spectrum of sexual dysfunctions, but the most commonly reported complaints are delayed ejaculation or anorgasmia and reduced sexual desire (84). Several mechanisms could be advocated including the agonist effect on serotonin receptors type 2 and the increase in PRL levels. ED is a frequent complaint as well (84,85). The relationship between the use of SSRI and ED can be secondary to loss of sexual desire but SSRI, in particular paroxetine, are also able to inhibit cholinergic receptors and nitric oxide synthase (86). In addition, it has been observed that SSRIs might down-regulate hypothalamic-pituitary-testis axis in depressed men (87).
If you are taking medications (alpha-blockers) for problems with an enlarged prostate, you should discuss your prostate medications with your doctor. Alpha-blockers also can cause lowering of the blood pressure. Thus your doctor will need to carefully watch your blood pressure when you start the PDE5 inhibitor. Common alpha-blockers include doxazosin (Cardura), terazosin (Hytrin), and tamsulosin (Flomax).
The most common inflatable prosthesis is the three-piece penile prosthesis. It is composed of paired cylinders, which doctors surgically insert inside the penis. Patients can expand the cylinders using pressurized fluid (see figure 3). Tubes connect the cylinders to a fluid reservoir and pump, which doctors also surgically implant. The reservoir is usually in the pelvis. A doctor places the pump in the scrotum. By pressing on the pump, sterile fluid transfers from the reservoir into the cylinders in the penis. An erection is produced primarily by expansion of the width of the penis, however, one model can increase in length a small amount also. Lock-out valves in the tubing prevent the fluid from leaving the cylinder until a release valve is pressed. By pressing the relief valve and gently squeezing the penis, the fluid within the cylinders transfers back into the reservoir.

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
Neurologic illnesses leading to ED have been recently reviewed (64). The most common of them (i.e., consequences of prostatic surgery, stroke and Parkinson’s disease) are not typical of younger age and, similarly to conditions less common but more typical of younger men, such as spinal cord injury, multiple sclerosis and spina bifida, the clinical features of the underlying disease are clearly apparent, being ED one of the multiple manifestations, rather than a harbinger of a subtle condition. Diagnosis of neurologic origin of ED is often quite simple, based on medical history and physical exam. The clinical management is a multidimensional and coordinated work of rehabilitation and medical therapy, which includes ICI injection of vaso-relaxant drugs, vacuum device and surgery (64).

For best results, men with ED take these pills about an hour or two before having sex. The drugs require normal nerve function to the penis. PDE5 inhibitors improve on normal erectile responses helping blood flow into the penis. Use these drugs as directed. About 7 out of 10 men do well and have better erections. Response rates are lower for Diabetics and cancer patients.


The recommended starting dose of tadalafil for use as needed for most patients is 10 mg taken orally approximately one hour before sexual activity. A doctor may adjust the dose higher to 20 mg or lower to 5 mg depending on efficacy and side effects. Doctors recommended that patients take tadalafil no more frequently than once per day. Some patients can take tadalafil less frequently since the improvement in erectile function may last 36 hours. Patients may take tadalafil with or without food. Tadalafil is currently the only PDE5 inhibitor that is FDA-approved for daily use for erectile dysfunction and is available in 2.5 mg or 5 mg dosages for daily use.
Tadalafil shares the common side effects of the PDE5 inhibitors, however, due to its effect on PDE11, another phosphodiesterase located in muscle, tadalafil has been associated with muscle aches. Back pain and muscle aches occur in less than 7% of men taking tadalafil and in most patients will go away without treatment within 48 hours. When treatment was necessary, acetaminophen (Tylenol) and nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Motrin, Advil) or naproxen (Aleve) were effective. Rarely do the muscle aches and back pain cause men to stop using tadalafil.

Our team includes a sex advisor/counselor who can help you understand what is making you anxious around sex, and give you techniques to decrease your anxiety about sex. He has also helped many of our younger patients get better at sex. We also have an exercise physiologist, who will work with you on both diet and exercise, which can have a profound effect on the quality of your erections.
As blood flows into the penis, the corpora cavernosa swell, and this swelling compresses the veins (blood vessels that drain the blood out of the penis) against the tunica albuginea. Compression of the veins prevents blood from leaving the penis. This creates a hard erection. When the amount of cGMP decreases by the action of a chemical called phosphodiesterase type 5 (PDE5), the muscles in the penis tighten, and the blood flow into the penis decreases. With less blood coming into the penis, the veins are not compressed, allowing blood to drain out of the penis, and the erection goes down.
The improvement of both man and woman sexual function in couples whose male partner is treated with PDE5i has been further confirmed by randomized clinical trials (RCTs) comparing the effectiveness of PDE5i vs. placebo in improving couple sexual function (91-95). In a more recent RCT, the use of vardenafil 10 mg oral dispersible tablets has been compared to the use of the drug itself in association with cognitive behavioral sexual therapy (CBST) for 10 weeks in 30 couples with ED male partners, randomly assigned to one study arm (96). Results from this RCT showed that vardenafil is able to improve male sexual function, but this improvement is maintained only in patients receiving both vardenafil and CBST. Furthermore, female sexual function and satisfaction are enhanced only in the arm with vardenafil and CBST combined therapy, thus suggesting that a therapy healing the couple is more effective and has a longer-lasting efficacy than the use of a medication focusing only on ED.

The liver is the largest gland and organ in the body. There are a variety of liver diseases caused by liver inflammation, scarring of the liver, infection of the liver, gallstones, cancer, toxins, genetic diseases, and blood flow problems. Symptoms of liver disease generally do not occur until the liver disease is advanced. Some symptoms of liver disease include jaundice, nausea and vomiting, easy bruising, bleeding excessively, fatigue, weakness, weight loss, shortness of breath, leg swelling, impotence, and confusion. Treatment of diseases of the liver depends on the cause.
Getting blood glucose under control is a good anti-ED tactic. Men with diabetes and poor blood glucose control are two to five times as likely to have ED as those with good control. One study in a group of men who had had type 1 diabetes for up to 15 years with minor complications found that intensive blood glucose control lowered the risk of ED compared with conventional treatment. A study in men with type 2 diabetes found that lowering A1C (average blood glucose in the past two to three months) below 7 percent and reducing blood pressure through a combination of medication, diet, and exercise improved sexual functioning.
ED is common among patients with cardiovascular diseases (CVD). Sexual problems usually precede the onset of CVD, and should, therefore, be considered as a risk factor for cardiac events. Similarly, patients with preexisting CVD are at increased risk of experiencing ED. Therefore, ED and CVD might be considered as two different clinical manifestations of the same systemic disease.19
CONDITIONS OF USE: The information in this database is intended to supplement, not substitute for, the expertise and judgment of healthcare professionals. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse effects, nor should it be construed to indicate that use of a particular drug is sage, appropriate or effective for you or anyone else. A healthcare professional should be consulted before taking any drug, changing any diet or commencing or discontinuing any course of treatment.

In rare cases, the drug Viagra ® can cause blue-green shading to vision that lasts for a short time. In rare cases, the drug Cialis® can cause or increase back pain or aching muscles in the back. In most cases, the side effects are linked to PDE5 inhibitor effects on other tissues in the body, meaning they are working to increase blood flow to your penis and at the same time impacting other vascular tissues in your body. These are not ‘allergic reactions'.

The brain is an often-overlooked erogenous zone. Sexual excitement starts in your head and works its way down. Depression can dampen your desire and can lead to erectile dysfunction. Ironically, many of the drugs used to treat depression can also suppress your sex drive and make it harder to get an erection, and they can cause a delay in your orgasm.
The 100 male subjects had a mean age of 37.09 (± 6.74) years. The quantity of alcohol consumed per day was 20.6 (± 9.07) standard drinks [8-42 drinks per day]. The mean duration of alcohol dependence was 8.59 (± 6.64) years. 87% of the subjects also used tobacco [chewing and / or smoking]. Seventy-two of the 100 subjects reported one or more sexual dysfunction. Four (4%) subjects reported aversion to sex to the extent that they had not attempted sexual intercourse in the last one year. Consequently, the prevalence of sexual dysfunction other than aversion to sex and low sexual desire, had to be calculated after excluding these 4 subjects.

It's not easy to get in the mood when you're overwhelmed by responsibilities at work and home. Stress can take its toll on many different parts of your body, including your penis. Deal with stress by making lifestyle changes that promote well-being and relaxation, such as exercising regularly, getting enough sleep, and seeking professional help when appropriate.


Carrying extra pounds can impact your sexual performance, and not just by lowering your self-esteem. Obese men have lower levels of the male hormone testosterone, which is important for sexual desire and producing an erection. Being overweight is also linked to high blood pressure and hardening of the arteries, which can reduce blood flow to the penis.
Unconventional CV risk factors, such as impaired erections during masturbation and reduced flaccid acceleration, are interesting parameters to implement in Sexual Medicine context, because they can help fill the gap of information on CV risk, left by the conventional risk factors (the so-called residual risk) (38). However, it should be recognized that not all the healthcare professionals who deal with the complaint of ED (i.e., general practitioners, diabetologists, cardiologists, sport physicians, nurses, etc.) have the facilities or competence for the specific assessment of these parameters. In contexts different than Sexual Medicine and Andrology, the assessment of conventional risk factors is certainly more convenient. Metabolic syndrome (MetS) represents a cluster of metabolic derangements easily and commonly evaluated in several different medical contexts. In a population of more than 600 subjects attending the Sexual Medicine and Andrology Unit of the University of Florence for ED, the presence of MetS was associated with an increased incidence of MACE during 4.3 years of follow-up in younger (first tertile of age: 18–52 years) (Figure 3, Panel A and B) but not in middle aged and older men (second and third tertiles of age: 53–60 and 61–88 years, respectively) (Figure 3, Panel B). Similar to MetS, the algorithms for estimating the risk of developing MACE are easily computed and they take into account factors largely available in a clinical setting. In Europe, the most commonly used algorithm is the SCORE, which takes into account age, smoking habits, systolic blood pressure and total cholesterol (26). These parameters are introduced in a calculation tool that returns the 10-year risk of developing the first MACE. The same estimated risk rate can obviously be derived from different combinations and extent of the single risk factors and, as aforementioned, age has a heavy weight in the amount of risk, even when the other parameters are normal. For overcoming this overestimation, the concept of vascular age, based on the predicted CV risk, has been introduced. Vascular age of a subjects with a specific CV risk profile corresponds to the chronological age of a subjects who has the same estimated risk but only due to chronological age, because of the absence of the other modifiable risk factors (i.e., a non-smoker, normotensive and normocholesterolemic subject) (39,40). Vascular age carries the advantage of easily and directly communicating the concept of high relative risk to patients, in particular to younger ones, who are by definition at low absolute risk (“Your CV risk is the same of a man that is 15 years older than you”). Based on this interesting and useful concept of vascular age, we recently studied the clinical consequences of having a high discrepancy between the estimated vascular and the actual chronological age in our population of men consulting for ED. In our sample, a greater difference between vascular and chronological age was associated with higher glucose and triglyceride levels as well as with impaired penile colour Doppler ultrasound parameters, suggesting a CV impairment (41). When evaluating the subset of men for whom information on incident MACE during a mean follow-up of 4.3 years was available, a greater difference between vascular and chronological age was associated with the incidence of MACE in younger, but not in older men (42).
Low intracavernosal nitric oxide synthase levels are found in people with diabetes, smokers, and men with testosterone deficiency. Interference with oxygen delivery or nitric oxide synthesis can prevent intracavernosal blood pressure from rising to a level sufficient to impede emissary vein outflow, leading to an inability to acquire or sustain rigid erection. Examples include decreased blood flow and inadequate intracavernosal oxygen levels when atherosclerosis involves the hypogastric artery or other feeder vessels and conditions, such as diabetes, that are associated with suboptimal nitric oxide synthase activity.
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